This paper discusses use of domain mapping matrix (DMM) to detect spatial conflicts across multiple design domains and use of octree-based voxel model for representation of these spatial conflicts. A framework has been developed to create octree-based voxel model linked with intended empty spaces in product, which are associated with design requirements, product lifecycle states and with connected design domains. Knowledge in system modelling language (SysML), is used to select criteria for building octree voxel model. Two case studies of coupled cavity travelling wave tube (CCTWT) slow wave structure (SWS) design and high power RF window design, have been taken to showcase the code capabilities. Octree voxels inside CAD platform, show and represent spatial conflicts, detected by associativity modelling of empty space blocks inside CAD along with the product knowledge in SysML model.